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Q85514: INFO: _DEBUG Must Be Defined When Linking to Debug Libraries

Article: Q85514
Product(s): Microsoft C Compiler
Version(s): winnt:1.0
Operating System(s): 
Keyword(s): kbnokeyword kbDebug kbMFC kbVC kbVC100 kbVC150 kbGrpDSMFCATL
Last Modified: 03-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft C/C++ for MS-DOS, version 7.0 
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, version 1.0 
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SUMMARY
=======

To link an application with the debugging version of the Microsoft Foundation
Class (MFC) libraries, the source code must define the _DEBUG macro at compile
time. Specify the name of the appropriate MFC library on the LINK command line
before the name of the appropriate C/C++ Run-time Library.

MORE INFORMATION
================

The debugging versions of the MFC libraries provide additional debugging
information in functions that the C/C++ run-time libraries normally provide
(such as "new" and "delete"). An attempt to link code compiled when the_DEBUG
macro is not defined with the debugging libraries may fail and LINK may generate
errors similar to the following:

  

  C:\...\MFC\lib\safxcwd.lib(memory.cpp) : error L2025: public:
     static void __near* __near __cdecl
     CObject::operator new(unsigned int) : symbol defined
     more than once

  

  C:\...\MFC\lib\safxcwd.lib(memory.cpp) : error L2025: public:
     static void __near __cdecl
     CObject::operator delete(void __near*) : symbol defined
     more than once

When compiling from the command line, use the /D compiler option to specify the
_DEBUG macro. For example, in Microsoft C/C++ version 7.0 for MS-DOS and Windows
or in Visual C++ version 1.0 or 1.5 for Windows, the command line might look
like the following:

     cl /AS /D_DEBUG test.cpp safxcwd.lib

In Visual C++ 32-bit edition version 1.0, the command line might look like the
following:

     cl /D_DEBUG /D_X86_ test.cpp nafxcwd

When you compile code that uses the Microsoft Foundation Classes in Programmer's
WorkBench (PWB), select the Use MFC Libraries option. (To do so, choose Language
Options from the Options menu, then choose Compiler Options, choose Additional
Compiler Options, and select MFC Libraries. Then choose OK.) PWB automatically
inserts the /D_DEBUG option when it compiles the debugging version of your
application. The PWB-generated LINK command specifies the appropriate Microsoft
Foundation Classes library and the appropriate C/C++ Run-time Library in the
correct order.

When you compile code that uses the Microsoft Foundation Classes in Visual
Workbench (VWB) in Visual C++ 1.0 or 1.5 for Windows, or Visual C++, 32-bit
edition, version 1.0, select the Use MFC Libraries option. (To do so, choose
Project from the Options menu, then select Use Microsoft Foundation Classes and
choose OK.) VWB automatically inserts the /D_DEBUG option when is compiles the
debugging version of your application. The VWB- generated LINK command specifies
the appropriate Microsoft Foundation Classes library and the appropriate C/C++
run-time library in the correct order.

In Visual C++, 32-bit Edition, version 2.0 and later, internal makefiles
automatically include a /D_DEBUG option on the build line debug targets.
Therefore, removing /D_DEBUG from the preprocessor command line options does not
cause an error.

Additional query words:

======================================================================
Keywords          : kbnokeyword kbDebug kbMFC kbVC kbVC100 kbVC150 kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:1.0
Issue type        : kbinfo

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